115 lines
3.7 KiB
Java
115 lines
3.7 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package websocket.snake;
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import java.util.Collection;
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import java.util.Collections;
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import java.util.Iterator;
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import java.util.Timer;
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import java.util.TimerTask;
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import java.util.concurrent.ConcurrentHashMap;
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import org.apache.juli.logging.Log;
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import org.apache.juli.logging.LogFactory;
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/**
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* Sets up the timer for the multi-player snake game WebSocket example.
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*/
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public class SnakeTimer {
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private static final Log log =
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LogFactory.getLog(SnakeTimer.class);
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private static Timer gameTimer = null;
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static final long TICK_DELAY = 100;
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private static final ConcurrentHashMap<Integer, Snake> snakes =
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new ConcurrentHashMap<>();
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protected static synchronized void addSnake(Snake snake) {
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if (snakes.size() == 0) {
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startTimer();
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}
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snakes.put(Integer.valueOf(snake.getId()), snake);
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}
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protected static Collection<Snake> getSnakes() {
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return Collections.unmodifiableCollection(snakes.values());
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}
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protected static synchronized void removeSnake(Snake snake) {
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snakes.remove(Integer.valueOf(snake.getId()));
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if (snakes.size() == 0) {
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stopTimer();
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}
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}
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protected static void tick() {
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StringBuilder sb = new StringBuilder();
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for (Iterator<Snake> iterator = getSnakes().iterator();
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iterator.hasNext();) {
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Snake snake = iterator.next();
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snake.update(getSnakes());
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sb.append(snake.getLocationsJson());
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if (iterator.hasNext()) {
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sb.append(',');
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}
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}
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broadcast(String.format("{\"type\": \"update\", \"data\" : [%s]}", sb.toString()));
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}
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protected static void broadcast(String message) {
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for (Snake snake : getSnakes()) {
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try {
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snake.sendMessage(message);
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} catch (IllegalStateException ise) {
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// An ISE can occur if an attempt is made to write to a
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// WebSocket connection after it has been closed. The
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// alternative to catching this exception is to synchronise
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// the writes to the clients along with the addSnake() and
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// removeSnake() methods that are already synchronised.
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}
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}
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}
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public static void startTimer() {
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gameTimer = new Timer(SnakeTimer.class.getSimpleName() + " Timer");
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gameTimer.scheduleAtFixedRate(new TimerTask() {
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@Override
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public void run() {
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try {
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tick();
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} catch (RuntimeException e) {
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log.error("Caught to prevent timer from shutting down", e);
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}
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}
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}, TICK_DELAY, TICK_DELAY);
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}
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public static void stopTimer() {
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if (gameTimer != null) {
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gameTimer.cancel();
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}
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}
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}
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